Truck bolster damping means



Nov. 15, 1955 E. H. PIRON TRUCK BOLSTER DAMPING MEANS 4 Sheets-Sheet 1Filed Jan. 30, 1950 INVENTOR I /Poh/ ATTOR YL Y Nov. 15, 1955 E. H.PIRON 2,723,629

TRUCK isoLsTER DAMPING MEANS Filed Jan. 50, 1950 4 Sheets-Sheet 2INVENTOR. 7/4 4/ 2&

BY @M A TTOR/V' Y Nov. 15, 1955 E. H. PIRON 2,723,629

TRUCK BOLSTER DAMPING MEANS Filed Jan. 30, 1950 4 Sheets-Sheet 3 LEG-EINVENTOR. 14 1 2204 A TTORNEY Nov. 15, 1955 E. H. PIRON 2,723,629

TRUCK BOLSTER DAMPING MEANS Filed Jan. 30, 1950 4 Sheets-Sheet 4 Tia-.7T

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a 2 a J/ a x %5 INVENTORI m /4 4 Bed United States Patent nice25,723,629 Patented Nov. 15, 1955 TRUCK BOLSTER DAMPING MEANS Emil H.Pirou, New York, N. Y., assignor to Transit Research Corporation, NewYork, N. Y., a corporation of New York Application January 30, 1950,Serial No. 141,211

3 Claims. (Cl. 105193) This invention relates to rail car trucks and thelike, wherein it is important to damp the swinging or oscillatingmovements of a body such as a truck bolster. The principal object is toprovide a new and improved motion damping means which will frictionallyresist such swinging in proportion to the violence of the shock whichproduces the swinging motion.

Rail trucks generally comprise a truck frame and a swing bolstersupported by the frame either on springs located at each end thereof orby swing links which may support the bolster directly, or which maysupport a spring plank which carries springs which in turn support thebolster. In any case, a lateral displacement of the truck sets up alateral motion of the car body which is carried by the bolster. Thismotion becomes a more or less continuous lateral oscillation unless itis damped. Conventionally the damping is done by shock absorbers or bysnubbers.

The main drawbacks to the use of prior art devices revolve arounddifiiculty of regulating those devices to respond in proportion to theviolence of the lateral shock and to the difficulty of maintaining theregulation once it has been made. For instance, the resistance ofhydraulic shock absorbers can be ascertained only by measurement in atesting machine and is never known with accuracy after short service. Inthe case of friction blocks the surfaces wear and must be adjusted atmore or less frequent intervals.

I have found that it is possible to damp such an oscillating motion byarranging to bias the bolster in its snubbers so that the action of thesnubbers can be reinforced by increasing their friction. Moreparticularly it is a principal object of this invention to provide meansoperative at a substantial distance from the center of a bolster tocause the bolster to partially rotate about its king pin in response toan impact thereagainst by the truck frame thereby causing a biasingaction proportionate to the violence of the lateral movement.

The most successful presently used snubber is composed of rubber blocksagainst which the bolster has rubbing engagement. If the lateral shockswere all of the same intensity such blocks could be adjusted for perfectsnubbing. Since the shocks vary greatly in intensity it thus becomes theproblem to obtain the effect of adjusting the blocks automatically toset up a friction proportionate to the violence of the shock. I havefound that this effect may be obtained by causing the bolster to biasagainst the snubber blocks.

More specifically it is the object of this invention to provide abolster support which may swing with subbing friction against frictionsurfaces, preferably of rubber, and to provide means for causing thebolster to rotate about an axis parallel to the friction surfaces inresponse to relative movement of the truck frame upon which the bolsteris supported.

The invention will be better understood with reference to theaccompanying drawings in which its application to one type of truck isillustrated and in which:

Figure 1 is a side elevation of a rail truck equipped with my improvedbolster snubbing arrangement,

Figure 2 is a top elevation of the truck of Figure 1,

Figure 3 is a detail view of the bolster of the truck of Figure 1 withits snubbers,

Figure 4 is a side elevation of the bolster of Figure 3,

Figure 5 is a top elevation of a rail truck showing a modification of myinvention incorporated therein,

Figure 6 is a side elevation of the truck of Figure 5,

Figure 7 is an enlarged vertical section taken along either line 7-7 ofFigure 5, and

Figure 8 is an enlarged vertical section taken along either line 88 ofFigure 5.

More particularly, 1 indicates the main side frames of a rail truck,which are connected at their ends to the housings 2 of axles 3. Theseside frames with the axle housings constitute the truck frame. The axlehousings include housings 4 for gears (not shown), one of which in eachcase is carried on the end of the propeller shaft 5 of a main drivingmotor 6, as shown in Figure 2. Each motor 6 is carried by a motorsupporting crossbeam 7 which is connected at eachend to a main framemember 1.

Between the motor supports 7 the truck bolster 8 is supported at eachend by large springs 9 which rest upon the side frames 1. These springs9 yieldingly resist both vertical and lateral swinging movements of thebolster 8 with respect to the side frames 1. Each end of the bolster 8has flat surfaces 10 (Figure 2) in rubbing contact with blocks of rubber11. These blocks of rubber are each supported by brackets 12 (seeFigures 1 and 2) mounted on the frames 1. These blocks of rubber 11 aretransom-like in their action in that they aid the springs 9 to transmitaccelerating and retarding forces between the side frames and thebolster, and they are also snubbers since they offer frictionalresistance to the swinging movements of the bolster. The blocks 11 maybe compressed against the surfaces 10 or merely loosely placed forcontact therewith.

The truck as described to this point is further described and claimed inmy co-pending application Serial #669,323, filed May 13, 1946, nowabandoned.

While the rubber to metal surfaces of the blocks 11 and the surfaces 10have a very satisfactory life, from a commercial standpoint, there aremany times when the play develops by wear because of lack of alertmaintenance. More important, damping by friction snubbers can notgenerally be regulated according to the violence of the shock. Theadditional construction now to be described causes the damping toincrease with an increase in the forces causing swinging movements ofthe bolster.

Extending outwardly from each side of the bolster near diagonallyopposite points are two brackets 13 which carry blocks of rubber 14 sopositioned that, with lateral swinging movements of the bolster, theywill contact a bracket 12 which is fixed to a side frame 1. Since thesecontacts are made only after sometswinging movement of the bolster hasoccurred and, then, only at diagonal points the bolster is slightlyrotated by the contact thus biasing it in the snubbers 10, 11. Theblocks 14 project out of the brackets 13 for a substantial distanceallowing for additional swinging movement of the bolster after thecontact is made.

The foregoing may be better understood with reference to Figure 3 inwhich it is seen that after contact of the blocks 14 with the brackets12 the blocks may be crushed or compressed by an amount d according tothe violence of the swinging movement of the bolster 8 thus developing alateral reaction F which varies with the value of d, so that The force Fis developed in a plane at a distance I from the center A of thebolster, which is its pivotal point, and produces a pivotal action equalto the moment Fl. Now, if b is the distance between the longitudinalcenter lines through the snubbers 10, ll, the moment Fl produces apressure on one rubber block 11 at each side of the truck. And if c isthe coefficient of friction between the surface and the rubber blocks11, the frictional force developed in the vertical transverse plane isthe frictional force is equal to the lateral force, the damping is asstrong as the oscillating force and there is no freedom of oscillation.

In order to preserve softness and some freedom of oscillation it isnecessary to make less than F or less than I or 201 less than b.

Although construction limitations generally do not permit thepossibility of making Zcl approach closely the value of b it is possibleto improve the approach and thus to improve greatly the damping effect.

Figures 5 to 8 illustrate a modification of my invention. In this casethe truck is composed of side rails 15 connected to the housings 16 foraxles 17. The axles 17 are supported by wheels 1%. Cross-beams 19support the driving motors 20. A bolster 21 is supported at each end bythree springs 22, 23 and 24 for relative vertical and lateral movementswith respect to the side frames 15. Brackets 25 extending outwardly fromthe side frames 15 support rubber blocks 26 at each side of and towardseach end of the bolster 21 for frictional contact with the bolster atthe surfaces 27. The blocks 26 and the surfaces 27 constitute thesnubbers.

The springs 22 and 23 are coil springs seated top and bottom in flatseats 28 provided in the bolster and in flat seats 29 provided on theside frames 1. They thus resist lateral movements of the bolster withrespect to the side frames. Please note that the spring 22 at one end ofthe bolster is diagonally opposite the spring 22 at the other end of thebolster. The springs 24 are seated top and bottom in rocker plates Si)in the bolster 21 and in rocker plates 31 on the side frames 15. Theserocker plates have rockers 32 seated in depressions 33, in eachinstance, which permit the springs 24 and the seats 30 and 31 to rock inresponse to lateral swinging movements of thebolster. The springs 24thus offer substantially less resistance to lateral swinging movementsof the bolster than do the springs 22 and 23. The result is that whenthe bolster 21 swings the supporting springs impart a slight rotation tothe bolster thus biasing it in its snubbers. The result is quite similarto that previously described.

Various changes may be made without departing from the spirit of myinvention and I therefore desire to be extended protection as defined bythe scope of the appended claims.

I claim:

1. In a rail truck, the combination of a main frame includingtransom-like cross-members, a bolster between said members, a set ofsprings supporting each end of said bolster from said frame, each ofsaid sets comprising a plurality of springs arranged side by side, thesprings composing each said set being oppositely offset from thelongitudinal center line of said bolster, one spring of each of saidsets having less load deflection resistance in the direction of theswinging movements of said bolster than the other spring in its set,friction motion damping means positioned on said cross members inslightly spaced relation with respect to the sides of said bolster, saidsprings by reason of the differential in resistance offered therebysetting up a couple in a horizontal plane causing partial rotation ofsaid bolster in response to swing movements thereof whereby said bolsterbiases against said damping means.

2. In a rail truck, a truck frame having transom-like cross-members,spring sets supporting each end of said bolster from said frame andadapted to yieldingly resist all relative vertical and lateral movementsthereof, each of said spring sets being composed of at least two springshaving their axes in a plane normal to the median plane verticallybisecting said bolster and seated on opposite sides of said plane, oneof the springs of each said set having a lower load deflectioncharacteristic in the direction of the lateral swinging movements ofsaid bolster than the other spring in its set, friction pads on eachside of said bolster near both ends of said bolster, said spring setsbeing reversely arranged with respect to each other, said springs byreason of their differential resistance to swinging movements of thebolster setting up a couple whereby said bolster biases against saidfriction pads in response to relative lateral movements between saidframe and said bolster.

3. In a rail truck, a truck frame having transom-like cross-members, aswing bolster between said members, spring sets supporting each end ofsaid bolster from said frame and yieldingly adapted to resist allrelative vertical and lateral movements thereof, each of said springsets being composed of at least two springs laterally spaced from eachother, one of the springs of each of said sets seating firmly againstsaid frame and said bolster, another of the springs of each said sethaving a spring cap on at least one end thereof, said spring cap havinga rocker exteriorly of its spring in rocking relation with respect tosaid bolster or said frame, said rocker having its axis normal to thedirection of the swinging movement of said bolster whereby said springsoifer different resistance to lateral swinging movements of saidbolster, friction pads carried by said transom-like members at each sideof and at each end of said bolster, the spring set at one end of saidbolster being arranged reversely to the spring set at the other endthereof, said springs by reason of their differential resistance toswinging movements of said bolster setting up a couple whereby saidbolster may bias against opposite friction pads during relative lateralmovements between said truck frame and said bolster.

References Cited in the file of this patent UNITED STATES PATENTS 35,410Bridges May 27, 1862 872,014 Price Nov. 26, 1907 1,632,077 Jablow June14, 1927 2,061,767 Hobson Nov. 24, 1936 2,094,557 Couch Sept. 28, 19372,159,138 Duryea May 23, 1939 2,492,337 Travilla Dec. 27, 19492,496,6,4,4- Travilla Feb. 7, 1950

